1. Field of the Invention
This patent concerns the sector of porterage equipment and particularly it concerns trolleys for shifting bulky and heavy objects. This patent specifically refers to a new motor-driven transport trolley with differentiated drive on both sides.
2. Description of the Related Art
Transport trolleys are already known for voluminous and/or heavy objects. These trolleys comprise two or more groups of broad wheels with small diameter. One of these trolleys is equipped with a rotating horizontal upper platform, on which the object to be transported rests, and a bar for towing and guiding the trolley, while trolleys without a rotating platform are placed at the rear.
The trolleys composed as described above are towed by hand by a number of persons.
Some trolleys are equipped with an electric motor which transmits motion to all the wheels of the trolley, in such a way as to make it less tiring to tow the object that is to be transported. Though convenient, these motor-driven trolleys still present certain drawbacks, including the need for powerful motors to start towing the transported object (pickup) and the difficulty of going round bends since, as the motor acts simultaneously on all the wheels, it is not easy to turn the trolley.
To overcome all the above problems, a new type of transport trolley has been designed and implemented, equipped with hydraulic motors which act independently on two or more wheels or groups of wheels placed on the two sides. As regards its main parts, the new transport trolley comprises a frame or bearing structure, two wheels or sets of wheels, one or more pairs of hydraulic motors, a rotating horizontal upper platform and a control unit for the various motors.
The frame or bearing structure connects and joins the various other parts. In particular it has a generally flat shape and the rotating horizontal platform is placed on top. This platform can turn with vertical axis in such a way as to allow the changing of the direction of the trolley with respect to the object transported.
On each of the two sides of the frame or structure is placed a set of wheels with small diameter and broad width. Each of the two wheels or sets of wheels receives motion, independently of the other, from one or more hydraulic motors. In other words, two or more hydraulic motors serve and move the wheels of a right-hand set and of a left-hand set.
The connection between the hydraulic motor or motors and the corresponding set of wheels may be achieved by means of cogged belts, chains with links or gears so that all the wheels in a set receive exactly the same motion at the same time.
The control unit oversees and controls the operation of the various motors and is equipped with a push-button panel or a control stick for controlling the movement of the trolley in the various directions. This push-button panel or control stick may be connected to the control unit by means of an electric cable, infrared rays or radio waves.
It is possible to allow for the various hydraulic motors to receive the fluid from a single pressure pump connected to all the motors by means of two or more valves; the pressure differentiation, and therefore the motion differentiation, is consequently determined by the closing or the partial or total opening of the valves. The fluid pressure pump may be included in the trolley; preferably it may be separate, for example transported on an auxiliary trolley moved by the operator. This solution offered by the new transport trolley allows each set of wheels, right and left, to be moved independently of the other, that is, by moving the two sets of wheels in a differentiated manner, it is possible to obtain forward and reverse motion and turning of the new transport trolley on the floor without any effort by the operator. The power may be supplied to the control unit by the mains or by batteries.